title: The Ahmed versus Baerveldt study: three-year treatment outcomes.
abstract: OBJECTIVE
  To compare 2 commonly used aqueous drainage devices for the treatment of refractory glaucoma.
  
  
  METHODS
  International, multicenter, randomized trial.
  
  
  METHODS
  Patients aged 18 years or older with uncontrolled or high-risk glaucoma refractory to maximum medical therapy, many of whom had failed trabeculoplasty and trabeculectomy.
  
  
  METHODS
  Eligible patients were randomized to an Ahmed-FP7 valve implant (New World Medical, Inc., Rancho Cucamonga, CA) or a Baerveldt-350 implant (Abbott Medical Optics, Inc., Santa Ana, CA) using a standardized surgical technique.
  
  
  METHODS
  The primary outcome was failure, defined as intraocular pressure (IOP) outside of the target range (5-18 mmHg, with ≥20% reduction from baseline) for 2 consecutive visits after 3 months, vision-threatening complications, de novo glaucoma procedures, or loss of light perception. Secondary outcome measures include IOP, medication use, visual acuity, complications, and interventions.
  
  
  RESULTS
  A total of 238 patients were enrolled and randomized; 124 received the Ahmed implant and 114 received the Baerveldt implant. Baseline characteristics were similar in both groups. Half the study group had secondary glaucoma, and 37% had previously failed trabeculectomy. The mean preoperative IOP was 31.4±10.8 mmHg on 3.1±1.0 glaucoma medications. Median baseline Snellen visual acuity was 20/100. At 3 years, the cumulative probability of failure was 51% in the Ahmed group and 34% in the Baerveldt group (P = 0.03). Mean IOP was 15.7±4.8 mmHg in the Ahmed group (49% reduction) and 14.4±5.1 mmHg in the Baerveldt group (55% reduction; P = 0.09). Mean number of glaucoma medications was 1.8±1.4 in the Ahmed group (42% reduction) and 1.1±1.3 in the Baerveldt group (65% reduction; P = 0.002). There was a moderate but similar decrease in visual acuity in both groups (P< 0.001). The 2 groups had similar complication rates (52% Ahmed, 62% Baerveldt; P = 0.12); however, the Baerveldt group had a higher rate of hypotony-related vision-threatening complications (0% Ahmed, 6% Baerveldt; P = 0.005). More interventions were required in the Baerveldt group, although the difference did not reach statistical significance (38% Ahmed, 50% Baerveldt; P = 0.07). Most complications were transient, and most interventions were slit-lamp procedures.
  
  
  CONCLUSIONS
  Both devices were effective in reducing IOP and glaucoma medications. The Baerveldt group had a lower failure rate and required fewer medications than the Ahmed group after 3 years, but it experienced more hypotony-related vision-threatening complications.
authors.affiliation: Department of Ophthalmology and Vision Sciences, University of Toronto Faculty of Medicine, Toronto, Canada; Department of Ophthalmology and Visual Science, Yale School of Medicine, New Haven, Connecticut.
authors.forename: Panos G
authors.initials: PG
authors.lastname: Christakis
authors.forename: James C
authors.initials: JC
authors.lastname: Tsai
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Kalenak
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.forename: Louis B
authors.initials: LB
authors.lastname: Cantor
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Kammer
authors.forename: Iqbal I K
authors.initials: II
authors.lastname: Ahmed
mesh_terms: D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use; D005260:Female; D005901:Glaucoma / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D011183:Postoperative Complications; D019919:Prosthesis Implantation; D012008:Recurrence; D014130:Trabeculectomy; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology
chemical_list: D000959:Antihypertensive Agents